Femtocells, also known as home base stations, Home E-UTRAN Node Bs (HeNBs) and Home Node Bs (HNBs), are base stations designed to serve relatively small geographic areas and are widely deployed at various locations such as homes, offices, shops, apartments, etc. These home base stations are used to improve radio coverage, increase throughput, reduce load on a macro-cellular network, and/or provide other benefits for network operators and/or users. Unlike macro base stations that are carefully deployed at specific known locations and maintained by network operators, home base stations may be flexibly deployed in an unplanned manner at any location by users but typically use licensed radio frequencies of the network operators.
A femtocell may support communication for one or more User Equipments (UEs) within its coverage. It may be desirable to know the location of the femtocell and/or a UE communicating with the femtocell. For example, it may be necessary to know the location of the femtocell in order to ensure that it is authorized to operate at its current location (e.g., is within a geographic area for which an associated network operator has a license to use the radio frequencies supported by the femtocell). As another example, the user of a UE may place an emergency call using the femtocell. The location of the UE may then be approximated by the location of the femtocell and used to send emergency assistance to the user. There are many other scenarios in which knowledge of the location of a femtocell may be useful or necessary.
In some situations, determining femtocell positions inside buildings using assisted GPS (A-GPS) or assisted GNSS (A-GNSS) may be difficult or unreliable due to lack of enough satellite vehicle (SV) signals (typically 4 or more) of sufficient strength that need to be acquired and measured by each femtocell in order to locate it. This can typically be a problem when attempting to locate a collection of femtocells (for example 3GPP HeNBs or HNBs) within a building or building complex (e.g. office building, shopping mall, hospital, hotel, apartment complex) since many of the femtocells may be deep inside the building or building complex and unable to receive many if any GPS or GNSS SV signals.
Therefore, there is a need for a method and system for determining locations of femtocells that can address the above issues.